This is my site and the system works well. But all things can be improved. I am in the process of building an improved, larger capacity kiln that is a little more controllable.
Surprisingly there is a lot variation in the quality of charcoal. Things like carbon content versus retained volatiles, friability (breakability) and fines(dust)affect heat output, handling and transport.
Not surprisingly, the Japanese have made charcoal making into an art. Many things like restaurant cooking, the tea ceremony and swordmaking each require a specific type of charcoal.
I visited a sworsmiths shop in Nagano last year and the charcoal was an art unto itself.
Don't let this deter you though.
Using the system Grant described or the one on my website will give you good forging fuel.
Dan